A computer virus is data that are programmed or embedded in a computer program to destroy the functionality of a computer. The virus may affect the normal use of the computer and be able to self-replicate, and the virus is usually presented in the form of a set of computer instructions or codes. An antivirus engine is a technical mechanism which can determine whether a particular program behaviour is a virus program (including a suspicious program). The antivirus engine is the main part of an anti-virus software and is a program for detecting and finding the virus. A virus database is a characteristic set of found viruses. In an anti-virus process, the characteristics 25 in the virus database are compared with all programs or files in a machine, and when the programs or files comply with these characteristics, they are determined as viruses.
During the research of the prior art, the inventor has found that every clearing procedure of antivirus engine is independent, that is, regardless of previous result output after the anti-virus engine scanning the files, the antivirus engine still scans all files next time, and the same virus file types may be found in the two scanning processes. It could be seen from above that, although the antivirus engine have powerful functions for clearing virus, when every time the 10 anti-virus engine scans all files, a lot of system resources will be occupied.